4 Commits

Author	SHA1	Message	Date
Dennis Heimbigner	231ae96c4b	Add support for Zarr string type to NCZarr ... * re: https://github.com/Unidata/netcdf-c/pull/2278 * re: https://github.com/Unidata/netcdf-c/issues/2485 * re: https://github.com/Unidata/netcdf-c/issues/2474 This PR subsumes PR https://github.com/Unidata/netcdf-c/pull/2278. Actually is a bit an omnibus covering several issues. ## PR https://github.com/Unidata/netcdf-c/pull/2278 Add support for the Zarr string type. Zarr strings are restricted currently to be of fixed size. The primary issue to be addressed is to provide a way for user to specify the size of the fixed length strings. This is handled by providing the following new attributes special: 1. **_nczarr_default_maxstrlen** — This is an attribute of the root group. It specifies the default maximum string length for string types. If not specified, then it has the value of 64 characters. 2. **_nczarr_maxstrlen** — This is a per-variable attribute. It specifies the maximum string length for the string type associated with the variable. If not specified, then it is assigned the value of **_nczarr_default_maxstrlen**. This PR also requires some hacking to handle the existing netcdf-c NC_CHAR type, which does not exist in zarr. The goal was to choose numpy types for both the netcdf-c NC_STRING type and the netcdf-c NC_CHAR type such that if a pure zarr implementation read them, it would still work and an NC_CHAR type would be handled by zarr as a string of length 1. For writing variables and NCZarr attributes, the type mapping is as follows: * "|S1" for NC_CHAR. * ">S1" for NC_STRING && MAXSTRLEN==1 * ">Sn" for NC_STRING && MAXSTRLEN==n Note that it is a bit of a hack to use endianness, but it should be ok since for string/char, the endianness has no meaning. For reading attributes with pure zarr (i.e. with no nczarr atribute types defined), they will always be interpreted as of type NC_CHAR. ## Issue: https://github.com/Unidata/netcdf-c/issues/2474 This PR partly fixes this issue because it provided more comprehensive support for Zarr attributes that are JSON valued expressions. This PR still does not address the problem in that issue where the _ARRAY_DIMENSION attribute is incorrectly set. Than can only be fixed by the creator of the datasets. ## Issue: https://github.com/Unidata/netcdf-c/issues/2485 This PR also fixes the scalar failure shown in this issue. It generally cleans up scalar handling. It also adds a note to the documentation describing that NCZarr supports scalars while Zarr does not and also how scalar interoperability is achieved. ## Misc. Other Changes 1. Convert the nczarr special attributes and keys to be all lower case. So "_NCZARR_ATTR" now used "_nczarr_attr. Support back compatibility for the upper case names. 2. Cleanup my too-clever-by-half handling of scalars in libnczarr.	2022-08-27 20:21:13 -06:00
Dennis Heimbigner	446348ed18	Add complete bitgroom support to NCZarr ... re: PR https://github.com/Unidata/netcdf-c/pull/2088 re: PR https://github.com/Unidata/netcdf-c/pull/2130 replaces: https://github.com/Unidata/netcdf-c/pull/2140 Changes: * Add NCZarr-specific quantize functions to the dispatch table. * Copy (modified) quantize code from libhdf5 to NCZarr * Add quantize invocation to zvar.c * Add support for _QuantizeBitgroomNumberOfSignificantDigits and _QuantizeGranularBitgroomNumberOfSignificantDigits to ncgen. * Modify nc_test4/tst_quantize.c to allow it to be used both for hdf5 and for nczarr. * Make dap4 properly handle quantize functions in dispatch table. * Add quantize attribute support to ncgen. Other changes: * Caught and fixed some S3 problems * Fixed some nczarr fillvalue problems. * Fixed some nczarr cache problems. * Cleanup some flaws in libdispatch/dinfermodel.c * Allow byterange requests to S3 be readable by dinfermodel.c/check_file_type * Remove the libnczarr ztracedispatch code (big change).	2022-01-24 15:22:24 -07:00
Dennis Heimbigner	8b9253fef2	Fix various problem around VLEN's ... re: https://github.com/Unidata/netcdf-c/issues/541 re: https://github.com/Unidata/netcdf-c/issues/1208 re: https://github.com/Unidata/netcdf-c/issues/2078 re: https://github.com/Unidata/netcdf-c/issues/2041 re: https://github.com/Unidata/netcdf-c/issues/2143 For a long time, there have been known problems with the management of complex types containing VLENs. This also involves the string type because it is stored as a VLEN of chars. This PR (mostly) fixes this problem. But note that it adds new functions to netcdf.h (see below) and this may require bumping the .so number. These new functions can be removed, if desired, in favor of functions in netcdf_aux.h, but netcdf.h seems the better place for them because they are intended as alternatives to the nc_free_vlen and nc_free_string functions already in netcdf.h. The term complex type refers to any type that directly or transitively references a VLEN type. So an array of VLENS, a compound with a VLEN field, and so on. In order to properly handle instances of these complex types, it is necessary to have function that can recursively walk instances of such types to perform various actions on them. The term "deep" is also used to mean recursive. At the moment, the two operations needed by the netcdf library are: * free'ing an instance of the complex type * copying an instance of the complex type. The current library does only shallow free and shallow copy of complex types. This means that only the top level is properly free'd or copied, but deep internal blocks in the instance are not touched. Note that the term "vector" will be used to mean a contiguous (in memory) sequence of instances of some type. Given an array with, say, dimensions 2 X 3 X 4, this will be stored in memory as a vector of length 2*3*4=24 instances. The use cases are primarily these. ## nc_get_vars Suppose one is reading a vector of instances using nc_get_vars (or nc_get_vara or nc_get_var, etc.). These functions will return the vector in the top-level memory provided. All interior blocks (form nested VLEN or strings) will have been dynamically allocated. After using this vector of instances, it is necessary to free (aka reclaim) the dynamically allocated memory, otherwise a memory leak occurs. So, the recursive reclaim function is used to walk the returned instance vector and do a deep reclaim of the data. Currently functions are defined in netcdf.h that are supposed to handle this: nc_free_vlen(), nc_free_vlens(), and nc_free_string(). Unfortunately, these functions only do a shallow free, so deeply nested instances are not properly handled by them. Note that internally, the provided data is immediately written so there is no need to copy it. But the caller may need to reclaim the data it passed into the function. ## nc_put_att Suppose one is writing a vector of instances as the data of an attribute using, say, nc_put_att. Internally, the incoming attribute data must be copied and stored so that changes/reclamation of the input data will not affect the attribute. Again, the code inside the netcdf library does only shallow copying rather than deep copy. As a result, one sees effects such as described in Github Issue https://github.com/Unidata/netcdf-c/issues/2143. Also, after defining the attribute, it may be necessary for the user to free the data that was provided as input to nc_put_att(). ## nc_get_att Suppose one is reading a vector of instances as the data of an attribute using, say, nc_get_att. Internally, the existing attribute data must be copied and returned to the caller, and the caller is responsible for reclaiming the returned data. Again, the code inside the netcdf library does only shallow copying rather than deep copy. So this can lead to memory leaks and errors because the deep data is shared between the library and the user. # Solution The solution is to build properly recursive reclaim and copy functions and use those as needed. These recursive functions are defined in libdispatch/dinstance.c and their signatures are defined in include/netcdf.h. For back compatibility, corresponding "ncaux_XXX" functions are defined in include/netcdf_aux.h. ```` int nc_reclaim_data(int ncid, nc_type xtypeid, void* memory, size_t count); int nc_reclaim_data_all(int ncid, nc_type xtypeid, void* memory, size_t count); int nc_copy_data(int ncid, nc_type xtypeid, const void* memory, size_t count, void* copy); int nc_copy_data_all(int ncid, nc_type xtypeid, const void* memory, size_t count, void** copyp); ```` There are two variants. The first two, nc_reclaim_data() and nc_copy_data(), assume the top-level vector is managed by the caller. For reclaim, this is so the user can use, for example, a statically allocated vector. For copy, it assumes the user provides the space into which the copy is stored. The second two, nc_reclaim_data_all() and nc_copy_data_all(), allows the functions to manage the top-level. So for nc_reclaim_data_all, the top level is assumed to be dynamically allocated and will be free'd by nc_reclaim_data_all(). The nc_copy_data_all() function will allocate the top level and return a pointer to it to the user. The user can later pass that pointer to nc_reclaim_data_all() to reclaim the instance(s). # Internal Changes The netcdf-c library internals are changed to use the proper reclaim and copy functions. It turns out that the places where these functions are needed is quite pervasive in the netcdf-c library code. Using these functions also allows some simplification of the code since the stdata and vldata fields of NC_ATT_INFO are no longer needed. Currently this is commented out using the SEPDATA \#define macro. When any bugs are largely fixed, all this code will be removed. # Known Bugs 1. There is still one known failure that has not been solved. All the failures revolve around some variant of this .cdl file. The proximate cause of failure is the use of a VLEN FillValue. ```` netcdf x { types: float(*) row_of_floats ; dimensions: m = 5 ; variables: row_of_floats ragged_array(m) ; row_of_floats ragged_array:_FillValue = {-999} ; data: ragged_array = {10, 11, 12, 13, 14}, {20, 21, 22, 23}, {30, 31, 32}, {40, 41}, _ ; } ```` When a solution is found, I will either add it to this PR or post a new PR. # Related Changes * Mark nc_free_vlen(s) as deprecated in favor of ncaux_reclaim_data. * Remove the --enable-unfixed-memory-leaks option. * Remove the NC_VLENS_NOTEST code that suppresses some vlen tests. * Document this change in docs/internal.md * Disable the tst_vlen_data test in ncdump/tst_nccopy4.sh. * Mark types as fixed size or not (transitively) to optimize the reclaim and copy functions. # Misc. Changes * Make Doxygen process libdispatch/daux.c * Make sure the NC_ATT_INFO_T.container field is set.	2022-01-08 18:30:00 -07:00
Dennis Heimbigner	59e04ae071	This PR adds EXPERIMENTAL support for accessing data in the ... cloud using a variant of the Zarr protocol and storage format. This enhancement is generically referred to as "NCZarr". The data model supported by NCZarr is netcdf-4 minus the user-defined types and the String type. In this sense it is similar to the CDF-5 data model. More detailed information about enabling and using NCZarr is described in the document NUG/nczarr.md and in a [Unidata Developer's blog entry](https://www.unidata.ucar.edu/blogs/developer/en/entry/overview-of-zarr-support-in). WARNING: this code has had limited testing, so do use this version for production work. Also, performance improvements are ongoing. Note especially the following platform matrix of successful tests: Platform | Build System | S3 support ------------------------------------ Linux+gcc | Automake | yes Linux+gcc | CMake | yes Visual Studio | CMake | no Additionally, and as a consequence of the addition of NCZarr, major changes have been made to the Filter API. NOTE: NCZarr does not yet support filters, but these changes are enablers for that support in the future. Note that it is possible (probable?) that there will be some accidental reversions if the changes here did not correctly mimic the existing filter testing. In any case, previously filter ids and parameters were of type unsigned int. In order to support the more general zarr filter model, this was all converted to char*. The old HDF5-specific, unsigned int operations are still supported but they are wrappers around the new, char* based nc_filterx_XXX functions. This entailed at least the following changes: 1. Added the files libdispatch/dfilterx.c and include/ncfilter.h 2. Some filterx utilities have been moved to libdispatch/daux.c 3. A new entry, "filter_actions" was added to the NCDispatch table and the version bumped. 4. An overly complex set of structs was created to support funnelling all of the filterx operations thru a single dispatch "filter_actions" entry. 5. Move common code to from libhdf5 to libsrc4 so that it is accessible to nczarr. Changes directly related to Zarr: 1. Modified CMakeList.txt and configure.ac to support both C and C++ -- this is in support of S3 support via the awd-sdk libraries. 2. Define a size64_t type to support nczarr. 3. More reworking of libdispatch/dinfermodel.c to support zarr and to regularize the structure of the fragments section of a URL. Changes not directly related to Zarr: 1. Make client-side filter registration be conditional, with default off. 2. Hack include/nc4internal.h to make some flags added by Ed be unique: e.g. NC_CREAT, NC_INDEF, etc. 3. cleanup include/nchttp.h and libdispatch/dhttp.c. 4. Misc. changes to support compiling under Visual Studio including: * Better testing under windows for dirent.h and opendir and closedir. 5. Misc. changes to the oc2 code to support various libcurl CURLOPT flags and to centralize error reporting. 6. By default, suppress the vlen tests that have unfixed memory leaks; add option to enable them. 7. Make part of the nc_test/test_byterange.sh test be contingent on remotetest.unidata.ucar.edu being accessible. Changes Left TO-DO: 1. fix provenance code, it is too HDF5 specific.	2020-06-28 18:02:47 -06:00